CVE-2018-16382 in Netwide Assembler
Summary
by MITRE
Netwide Assembler (NASM) 2.14rc15 has a buffer over-read in x86/regflags.c.
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Analysis
by VulDB Data Team • 03/20/2020
The vulnerability identified as CVE-2018-16382 affects Netwide Assembler version 2.14rc15, a widely used open-source assembler for x86 and x86-64 architectures. This issue manifests as a buffer over-read condition within the x86/regflags.c source file, representing a critical memory safety flaw that could potentially be exploited by malicious actors. The vulnerability occurs during the processing of assembly code where the assembler fails to properly validate buffer boundaries, leading to memory access violations that may result in unpredictable behavior or system compromise.
The technical flaw stems from inadequate input validation mechanisms within the register flags handling code of NASM's x86 architecture support module. When processing certain assembly instructions or operands, the code attempts to read beyond the allocated buffer boundaries, specifically in the context of register flag management operations. This over-read condition allows an attacker to potentially access memory locations that should remain protected, creating opportunities for information disclosure, denial of service, or even remote code execution depending on the specific exploitation scenario. The vulnerability is classified under CWE-125 as an out-of-bounds read, which represents a fundamental memory safety issue that has been consistently identified as a primary attack vector in software security assessments.
The operational impact of this vulnerability extends beyond simple memory corruption, as NASM is commonly used in build systems, compiler toolchains, and development environments where malicious input could be introduced through compromised assembly source files or during automated compilation processes. Attackers could potentially craft specially formatted assembly code that triggers the buffer over-read when processed by NASM, leading to system instability or exploitation of the underlying memory layout. The vulnerability is particularly concerning in environments where NASM processes untrusted assembly code or where assembly source files are generated dynamically from user input, as these scenarios provide ideal conditions for exploitation. This flaw aligns with ATT&CK technique T1059.001 for execution through command and scripting interpreter, as the vulnerability could enable attackers to execute malicious code through compromised assembly processing workflows.
Mitigation strategies for CVE-2018-16382 should prioritize immediate patching of NASM installations to versions that address the buffer over-read condition in x86/regflags.c. System administrators should also implement input validation measures for assembly code processing, particularly in automated build environments where untrusted code may be processed. Additional defensive measures include deploying memory protection mechanisms such as stack canaries, address space layout randomization, and heap metadata protection to reduce the effectiveness of potential exploitation attempts. Organizations should also consider implementing sandboxing techniques when processing assembly code and establishing strict access controls for systems that utilize NASM in automated workflows. The vulnerability highlights the importance of regular security updates and thorough code review processes, particularly for tools that handle low-level code processing and are integral components of software development toolchains.